Researchers at Poland-based Security Explorations said they have sent Oracle a proof-of-concept on the discovery.

"The code successfully demonstrates a complete JVM sandbox bypass in the environment of a latest Java SE software (version 7 Update 7 released on Aug 30, 2012)," wrote Adam Gowdiak, founder of Security Explorations. "The reason for it is a new security issue discovered, that made exploitation of some of our not yet addressed bugs possible to exploit again."

Technical details on the flaw will not be provided to the public until Oracle investigates the proof-of-concept, the company said.

Gowdiak did confirm that Oracle's update did resolve the three flaws as intended.

This isn't the first time that Gowdiak and his firm have found flaws with Oracle's Java plugin. Security Explorations privately disclosed 19 Java 7 security issues, including last week's zero-day exploit, in April.

While two of the 19 flaws were addressed in the latest update from Oracle, Gowdiak said that its disclosure of the new flaw has a direct connection with the remaining unfixed flaws.

"That's a completely new vulnerability. It however makes our past, not yet addressed issues possible to exploit again in the environment of the recent Java 7 Update 7," Gowdiak said.

While Oracle did push through an out-of-band update last week for the zero-day flaw, the remaining unpatched vulnerabilities may get a fix with Oracle's next quarterly update, which is estimated to arrive sometime in the next month.